The present invention relates to an electrolytic bath which can be used for various kinds of electrolysis, and more particularly relates to an electrolytic bath in which an electrochemical treatment is conducted in order to inhibit deterioration in performance caused by micro-organisms contained in the water to be treated, and in order to eliminate the smell of bleach from drinking water which is supplied through the water supply system for domestic and business use. More particularly, the present invention relates to an electrolytic bath for sterilization of photographic processing solutions utilized for the processes of color development, bleaching, bleaching and fixing, fixing, stabilizing, and washing, and further for sterilization of water to be used in a swimming pool, for paper making, in a heat exchanger, for drinking, for fish breeding, in a public bath, and etc, by processing water electrochemically.
Various kinds of water solutions are conventionally utilized for various purposes. When these water solutions provide adequate nourishment, or the temperature is suitable for propagation of bacteria, bacteria breed in the solution, so that the performance of the solution is deteriorated and the bred bacteria float in the processing apparatus and damage its function.
For example, in the case of photographic light sensitive material, a photographic paper is processed through the processes of color development, bleaching and fixing, water washing and/or stabilization, and finally the photographic paper is dried. In the aforementioned photographic processes, various kinds of photographic processing solutions such as a color developing agent, bleaching agent, bleaching and fixing agent, fixing agent, stabilizer, and washing water, are utilized. The aforementioned light sensitive materials contain gelatin and various inorganic salts, so that they provide an adequate environment for bacteria to breed. Consequently, the following problems are caused: bacteria mixed into the aforementioned photographic processing solutions breed and the efficiency of photographic material processing is lowered; unevenness is caused in the color of a print; and obtained images are stained because of mold. In order to prevent the deterioration of photographic processing solutions, disinfectant or an anti-mold agent is conventionally added to the solutions so that the aforementioned bacteria can be eliminated. According to the aforementioned method, a large amount of anti-mold agent needs to be added, so that the added anti-mold agent tends to remain in the photographic solutions or the aforementioned light sensitive material and exerts a bad influence on the light sensitive material. Further, most of the aforementioned anti-mold agents are poisonous, and their use is regulated. Furthermore, when the anti-mold agent is used for a certain period of time, resistance is generated in the bacteria, so that another anti-mold agent must be applied to eliminate the bacteria.
In the water of public pools, a large number of microorganisms such as coliform bacilluses and bacteria live, and they are harmful to the eyes of a swimmer. In order to protect the swimmer, a disinfectant such as sodium hypochlorite is added to the water of the pool for disinfection. A chloric reagent such as sodium hypochlorite and liquid chloride is used since they are effective for disinfection. The chloric reagent itself, and its decomposed products, also cause problems, such as sore eyes and skin eruptions, which can be serious with weak infants. Since the chloric reagent decomposes, it can not be used continuously, so that water must be supplied every day. Accordingly, a large amount of water is consumed for a swimming pool and the cost of disinfectant to be used becomes a heavy burden.
In this modern "information society", the demand for various kinds of papers, especially papers of high quality, has increased. These papers are made from pulp for paper-making use through various processes. Pulp is cleaned in order to remove unnecessary components before it is processed in the paper-making process. An adequate temperature of the aforementioned pulp is maintained, and the pulp contains adequate nourishment, so that mold and bacteria tend to breed in the pulp and a large amount of mold and bacteria remain in the final product, which results in deterioration of the quality of the paper. Accordingly, an anti-mold agent and disinfectant are added to the large amount of water used in the aforementioned cleaning process in order to prevent the deterioration of the paper. However, the following problems are caused in the aforementioned method: the costs of the anti-mold agent and disinfectant are raised; and deterioration of quality due to the residual anti-mold agent and disinfectant is caused.
Recently, the number of air conditioners has increased as the number of condominiums and office buildings has increased in which air conditioners are installed. In the condominium and office building, a cooling tower, which is a heat exchanging unit, is installed on the roof of the building. When the same water is used in the heat exchanging unit over a long period of time, microorganisms such as mold and bacteria breed in the water and precipitate on the heat exchanging surface of the aforementioned heat exchanging unit. Consequently, heat exchanging performance is deteriorated and piping can become blocked by a lump of microorganisms, which leads to the decrease in heat exchanging ability. A large amount of discharged microorganisms causes serious problems such as corrosion of the piping.
Recently, consumption of water for baths has increased. The temperature of bath water is approximately 40.degree. C., which is the optimum temperature for microorganisms to breed, so that microorganisms breed very quickly, and even faster when the water becomes dirty. The size of a microorganism is so minute that it is difficult to remove it from water by means of filtering. In the case of a public bath, the amount of water to be processed is large, so that the cost of processing can be greatly reduced when dirty bath water can be processed by a simple processing operation.
Recently, a large number of fish have been bred in breeding ponds, and supplied to the market. When fish are bred in a breeding pond, various kinds of chemicals are added into the water in a breeding pond in order to exterminate microorganisms, since the microorganisms contaminate fish, and lessen the value of the fish. Food is supplied to the fish in the breeding pond, and consequently, a large amount of chemicals, anti-mold agent and disinfectant, which are harmful to humans, are accumulated in the fish, and the contaminated fish come on the market.
Drinking water is supplied to houses and restaurants from a reservoir through a water supply system after it has been sterilized in a purification plant. Sterilization is generally conducted by chlorite gas. Microorganisms are mostly exterminated by the sterilization by chloric gas. On the other hand, the residual chloride affects the taste and flavor of drinking water.
Drinking water is very important for our health, so that it is essential to prevent microorganisms from breeding in drinking water and it is also important to exterminate microorganisms living in water. Mold and microorganisms are mostly disinfected by means of chloride disinfection. However, sources of water such as rivers and lakes are contaminated by various kinds of organisms, so that more chloride than that is required to exterminate the microorganisms is added to the water. Accordingly, effective chloride components such as an organic halide, hypochlorous acid ions and residual chloride are generated. In order to solve the aforementioned problems, methods of disinfection in which chloride is not utilized, have been proposed.
For example, a method to improve the quality of water by the processing of ozone addition or the processing of activated carbon absorption has been proposed. However, when water is processed by the aforementioned method in a purification plant, the cost is very high. Furthermore, there is still a problem that even if water is processed in a purification plant, microorganisms are bred again during the conveyance of water from the purification plant to the consumer.
As described above, the main method of disinfection of drinking water is the chloride method. When the chloride method is adopted, hypochlorous acid ions are generated or chloride gas remains so that the smell of bleach is caused. In order to remove the smell of bleach, the following method is adopted: hypochlorous acid ions (effective chloride), which are the source of the smell, are absorbed by activated carbon; and effective chloride is reduced by oxidizing the activated carbon.
However, this method is disadvantageous in that: since there is a limit in the absorbing capacity of activated carbon, defective chloride decomposition is caused after activated carbon has been used for a certain period of time; and replacement of activated carbon is troublesome and expensive, so that the smell of bleach can not be eliminated completely.
Consequently, there is a demand for a water processing method replacing hypochlorous acid ions which are harmful to humans and tend to affect the taste of water.
In order to prevent the aforementioned problems, various chemicals such as an anti-mold agent and precipitation inhibitor are added to the water to be processed, or various kinds of filters are installed in the intermediate portion of piping. When chemicals are added, residual chemicals affect the quality of water to be processed as described before, and the cost is increased. Furthermore, microorganisms become resistant to the chemicals when the chemicals are used for a certain period of time, so that another chemical must be used.
In order to solve the aforementioned problems of the conventional technique, the applicant has proposed a method in which water to be processed can be electrochemically processed so that the water can be disinfected and the bleach smell can be removed (which has been disclosed in Japanese Patent Application 326846/1989. According to the electrochemical processing method described above, the water to be processed can be positively processed without leaving the residual chemical in the water. In the aforementioned electrochemical processing, the electrode to be utilized is not limited particularly. However, a carbon electrode is preferably used for the reasons that: no harmful substance is contained in carbon; the cost is low; bacteria are easily absorbed; the over-voltage is high; and an unnecessary reaction such as generation of oxygen can be inhibited.
The carbon electrode has the aforementioned advantages. On the other hand, it has a disadvantage in that when oxygen gas is generated, the carbon electrode is quickly consumed. Accordingly, when a carbon electrode is used over a long period of time, it is consumed gradually and the distance between the electrodes is increased, so that the voltage is increased or carbon particles flow out in the processing solution. Accordingly, the carbon electrode must be finally replaced with a new one. In general, replacement of the electrode must be conducted after the entire electrolytic bath has been overhauled. Consequently, the replacing work is very complicated and the efficiency is lowered.